package com.example.mq.mqserver.datacenter;

import com.example.mq.common.MqException;
import com.example.mq.mqserver.core.Binding;
import com.example.mq.mqserver.core.Exchange;
import com.example.mq.mqserver.core.MSGQueue;
import com.example.mq.mqserver.core.Message;
import com.sun.org.apache.bcel.internal.generic.NEW;

import java.io.IOException;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;

/**
 * 使用这个类统一管理内存中的数据
 * 该类后续会提供一些方法，可能会在多线程下使用，因此要注意线程安全问题
 */
public class MemoryDataCenter {
    // key 是 exchangeName , value 是 Exchange 对象
    private ConcurrentHashMap<String, Exchange> exchangeMap = new ConcurrentHashMap<>();
    // key 是 queueName , value 是 MSGqueue 对象
    private ConcurrentHashMap<String, MSGQueue> queueMap = new ConcurrentHashMap<>();
    // 第一个 key 是 exchangeName , 第二个 Key 是 queueName
    private ConcurrentHashMap<String, ConcurrentHashMap<String, Binding>> bindingsMap = new ConcurrentHashMap<>();
    // key 是 messageId, Value 是一个 Message 对象
    private ConcurrentHashMap<String, Message> messageMap = new ConcurrentHashMap<>();
    // key 是 queueName , Value 是一个 Message的链表
    private ConcurrentHashMap<String, LinkedList<Message>> queueMessageMap = new ConcurrentHashMap<>();
    // 第一个key 是 queueName , 第二个 Key 是 messageId
    private ConcurrentHashMap<String, ConcurrentHashMap<String, Message>> queueMessageWaitAckMap = new ConcurrentHashMap<>();

    public void insertExchange(Exchange exchange) {
        exchangeMap.put(exchange.getName(), exchange);
        System.out.println("[MemoryDataCenter] 新交换机添加成功！exchangeName=" + exchange.getName());

    }

    public Exchange getExchange(String exchangeName) {
        return exchangeMap.get(exchangeName);
    }

    public void deletaExchange(String exchangeName) {
        exchangeMap.remove(exchangeName);
        System.out.println("[MemoryDataCenter] 交换机删除成功！exchangeName=" + exchangeName);
    }

    public void insertQueue(MSGQueue queue) {
        queueMap.put(queue.getName(), queue);
        System.out.println("[MemoryDataCenter] 新队列添加成功！queueName=" + queue.getName());
    }

    public MSGQueue getQueue(String queueName) {
        return queueMap.get(queueName);
    }

    public void deleteQueue(String queueName) {
        queueMap.remove(queueName);
        System.out.println("[MemoryDataCenter] 队列删除成功！queueName=" + queueName);
    }

    public void insertBinding(Binding binding) throws MqException {
        // 先使用 exchangeName 查一下，对应的 HashMap 是否存在，不存在就创建
        ConcurrentHashMap<String, Binding> bindingMap = bindingsMap.computeIfAbsent(binding.getExchangeName(),
                k -> new ConcurrentHashMap<>());
        // 再根据 queueName 查一下，如果 binding 存在，就抛出异常，不存在才能插入
        synchronized (bindingMap) {
            if (bindingMap.get(binding.getQueueName()) != null) {
                throw new MqException("[MemoryDataCenter] 绑定已经存在！exchangeName=" + binding.getExchangeName() +
                        ", queueName=" + binding.getQueueName());
            }
            bindingMap.put(binding.getQueueName(), binding);
        }
        System.out.println("[MemoryDataCenter] 新绑定添加成功！exchangeName=" + binding.getExchangeName()
                + ", queueName=" + binding.getQueueName());
    }

    // 获取绑定，写两个版本
    // 1. 根据 exchangeName 和 queueNane 确定唯一的 Binding
    public Binding getBinding(String exchangeName, String queueName) {
        ConcurrentHashMap<String, Binding> bindMap = bindingsMap.get(exchangeName);
        if (bindMap == null) {
            return null;
        }
        return bindMap.get(queueName);
    }

    // 2. 根据 exchangeName 获取到 所有的 Binding
    public ConcurrentHashMap<String, Binding> getBindings(String exchangeName) {
        return bindingsMap.get(exchangeName);
    }

    public void deleteBinding(Binding binding) throws MqException {
        ConcurrentHashMap<String, Binding> bindMap = bindingsMap.get(binding.getExchangeName());
        if (bindMap == null) {
            // 该交换机没有绑定任何队列
            throw new MqException("[MemoryDataCenter] 绑定不存在！exchangeName=" + binding.getExchangeName() + ", queueName"
                    + binding.getQueueName());
        }
        bindMap.remove(binding.getQueueName());
        System.out.println("[MemoryDataCenter] 绑定删除成功！exchangeName=" + binding.getExchangeName()
                + ", queueName=" + binding.getQueueName());
    }

    // 添加消息
    public void addMessage(Message message) {
        messageMap.put(message.getMessageId(), message);
        System.out.println("[MemoryDataCenter] 新消息添加成功！messageId=" + message.getMessageId());
    }

    // 根据 id 查询消息
    public Message getMessage(String messageId) {
        return messageMap.get(messageId);
    }

    // 根据 id 删除消息
    public void removeMessage(String messageId) {
        messageMap.remove(messageId);
        System.out.println("[MemoryDataCenter] 消息删除成功！messageId=" + messageId);
    }

    // 发送消息到指定队列
    public void sendMessage(MSGQueue queue, Message message) {
        // 把消息放到对应的队列中
        // 先根据队列名字，找到该队列对应的消息链表
        LinkedList<Message> messages = queueMessageMap.computeIfAbsent(queue.getName(), k -> new LinkedList<>()
        );
        synchronized (messages) {
            messages.add(message);
        }
        // 在这里把该消息也往消息中心插入一下
        // 这里就算消息中心已经存在消息，重复插入也没关系
        // messageId相同，对应的 message 的内容也一定是一样的（服务器代码不会对 Message 内容做出修改 basicProperties 和 body）
        addMessage(message);
        System.out.println("[MemoryDataCenter] 消息被投递到队列中！messageID=" + message.getMessageId() + ", queueName=" +
                queue.getName());
    }

    // 从队列中获取指定消息
    public Message pollMessage(String queueName) {
        // 根据队列名，查找一下，对应的队列的消息链表
        LinkedList<Message> messages = queueMessageMap.get(queueName);
        // 如果没找到说明，队列中没有任何消息
        if (messages == null) {
            return null;
        }
        synchronized (messages) {
            if (messages.size() == 0) {
                return null;
            }
            // 链表中有元素，就进行头删除
            Message curMessage = messages.remove(0);
            System.out.println("[MemoryDataCenter] 消息从队列中取出！messageId=" + curMessage.getMessageId());
            return curMessage;
        }
    }


    // 获取指定队列中的消息个数
    public int getMessageCount(String queueName) {
        LinkedList<Message> messages = queueMessageMap.get(queueName);
        if (messages == null) {
            return 0;
        }
        if (messages.size() == 0){
            return 0;
        }
        synchronized (messages) {
            System.out.println("messageSize=" + messages.size());
            return messages.size();
        }
    }

    // 添加未确认的消息
    public void addMessageWaitAck(String queueName, Message message) {
        ConcurrentHashMap<String, Message> messageHashMap = queueMessageWaitAckMap.computeIfAbsent(queueName,
                k -> new ConcurrentHashMap<>());
        messageHashMap.put(message.getMessageId(), message);
        System.out.println("[MemoryDataCenter] 消息进入待确认队列！messageId=" + message.getMessageId());
    }

    // 删除消息（已确认过）
    public void removeMessageWaitAck(String queueName, String messageId) {
        ConcurrentHashMap<String, Message> messageHashMap = queueMessageWaitAckMap.get(queueName);
        if (messageHashMap == null) {
            return;
        }
        messageHashMap.remove(messageId);
        System.out.println("[MemoryDataCenter] 消息从待确认队列中删除！messageId=" + messageId);
    }

    // 获取到指定的未确认消息
    public Message getMessageWaitAck(String queueName, String messageId) {
        ConcurrentHashMap<String, Message> messageHashMap = queueMessageWaitAckMap.get(queueName);
        if (messageHashMap == null) {
            return null;
        }
        return messageHashMap.get(messageId);
    }

    // 从硬盘上读取数据，把硬盘之前持久化存储的各个维度的数据恢复到内存中
    public void recovery(DiskDataCenter diskDataCenter) throws IOException, MqException, ClassNotFoundException {
        // 0. 清空之前的所有数据
        exchangeMap.clear();
        queueMap.clear();
        bindingsMap.clear();
        messageMap.clear();
        queueMessageMap.clear();
        // 1. 恢复所有的交换机数据
        List<Exchange> exchanges = diskDataCenter.selectAllExchanges();
        for (Exchange exchange : exchanges) {
            exchangeMap.put(exchange.getName(), exchange);
        }
        // 2. 恢复所有的队列数据
        List<MSGQueue> queues = diskDataCenter.selectAllQueues();
        for (MSGQueue queue : queues) {
            queueMap.put(queue.getName(), queue);
        }
        // 3.恢复所有绑定数据
        List<Binding> bindings = diskDataCenter.selectAllBindings();
        for (Binding binding : bindings) {
            ConcurrentHashMap<String, Binding> bindingMap = bindingsMap.computeIfAbsent(binding.getExchangeName(),
                    k -> new ConcurrentHashMap<>());
            bindingMap.put(binding.getQueueName(), binding);
        }
        // 4.恢复所有消息数据
        // 遍历所有的队列，根据每个队列的名字，来获取所有的消息
        for (MSGQueue queue : queues) {
            LinkedList<Message> messages = diskDataCenter.loadAllMessageFromQueue(queue.getName());
            queueMessageMap.put(queue.getName(), messages);
            for (Message message : messages) {
                messageMap.put(message.getMessageId(), message);
            }
        }
        // 注意针对 “未确认的消息” 这部分内存中的数据，不需要从硬盘恢复，
        // 一旦在等待 Ack 的过程中，服务器重启了，此时这些 “未被确认的消息”,就被恢复成“未被取走的消息”
        // 这个消息在硬盘上存储的时候，就代表 “未被取走”
    }
}
